Perfusion quality odds (PEQUOD) trial: validation of the multifactorial dynamic perfusion index as a predictor of cardiac surgery-associated acute kidney injury.

OBJECTIVES: The multifactorial dynamic perfusion index was recently introduced as a predictor of cardiac surgery-associated acute kidney injury. The multifactorial dynamic perfusion index was developed based on retrospective data retrieved from the patient files. The present study aims to prospectively validate this index in an external series of patients, through an on-line measure of its various components. METHODS: Inclusion criteria were adult patients undergoing cardiac surgery with cardiopulmonary bypass. Data collection included preoperative factors and cardiopulmonary bypass-related factors. These were collected on-line using a dedicated monitor. Factors composing the multifactorial dynamic perfusion index are the nadir haematocrit, the nadir oxygen delivery, the time of exposure to a low oxygen delivery, the nadir mean arterial pressure, cardiopulmonary bypass duration, the use of red blood cell transfusions and the peak arterial lactates. RESULTS: Two hundred adult patients were investigated. The multifactorial dynamic perfusion index had a good (c-statistics 0.81) discrimination for cardiac surgery-associated acute kidney injury (any stage) and an excellent (c-statistics 0.93) discrimination for severe patterns (stage 2-3). Calibration was modest for cardiac surgery-associated acute kidney injury (any stage) and good for stage 2-3. The use of vasoconstrictors was an additional factor associated with cardiac surgery-associated acute kidney injury. CONCLUSIONS: The multifactorial dynamic perfusion index is validated for discrimination of cardiac surgery-associated acute kidney injury risk. It incorporates modifiable risk factors, and may help in reducing the occurrence of cardiac surgery-associated acute kidney injury.

A systematic review of biocompatible cardiopulmonary bypass circuits and clinical outcome.

This systematic review and meta-analysis explores the clinical efficacy of biocompatible surfaces for cardiopulmonary bypass in adults. Thirty-six randomized controlled trials were retrieved for a total of 4360 patients. Patients treated with biocompatible circuits had a lower rate of packed red cells transfusions and atrial fibrillation, and shorter durations of stay in the intensive care unit. When the analysis was limited to high-quality studies, only a reduction in atrial fibrillation rate and a shorter stay in the intensive care unit remained significantly associated with the use of biocompatible surfaces. Using biocompatible surfaces without other measures to contain blood activation results in a limited clinical benefit.

Surgical reexploration after cardiac operations: why a worse outcome?

BACKGROUND: Surgical reexploration due to postoperative bleeding occurs in 2% to 6% of cardiac surgical patients and is accompanied by increased morbidity and mortality. In this study, we addressed the postoperative course of patients needing surgical reexploration, with specific respect to the timing of reexploration and the transfusional needs as determinants of morbidity and mortality. METHODS: This was a retrospective study of 232 patients having undergone surgical reexploration owing to postoperative bleeding after cardiac operations, compared with a control, propensity-matched group. RESULTS: Patients in the surgical reexploration group had greater morbidity (low cardiac output, acute renal failure, sepsis) and longer mechanical ventilation time and intensive care unit stay than did control patients, and a significantly higher mortality rate (14.2% versus 3.4%, p = 0.001). The timing of surgical reexploration was not associated with morbidity or mortality. The amount of packed red cells transfused was significantly associated with increased morbidity (acute renal failure, low cardiac output syndrome, sepsis), with mechanical ventilation time and intensive care unit stay, and with the mortality rate (0.25% increase for each unit transfused). CONCLUSIONS: The main determinant of morbidity and mortality for patients requiring a surgical reexploration after cardiac operations is the amount of packed red cells transfused. Delaying the timing of reexploration may represent a risk factor only when the delay creates the need for an excessive use of allogeneic blood products, or in the presence of clinical signs of cardiac tamponade.

Oxygen delivery during cardiopulmonary bypass and acute renal failure after coronary operations.

BACKGROUND: The degree of hemodilution during cardiopulmonary bypass has recently been identified as an independent risk factor for acute renal failure after cardiac operations. In this prospective observational study we have investigated the role of the lowest oxygen delivery, lowest hematocrit, and pump flow during cardiopulmonary bypass as possible risk factors for acute renal failure and renal dysfunction. METHODS: One thousand forty-eight consecutive patients undergoing coronary operations have been studied. For each patient we have recorded the lowest hematocrit on cardiopulmonary bypass, the correspondent lowest oxygen delivery, and the pump flow around the time of these determinations. The three variables have been explored in a multivariable model as possible risk factors for acute renal failure and postoperative serum creatinine levels increase. The role of transfusions in determining acute renal failure was subsequently included in the model. RESULTS: The best predictor for acute renal failure and peak postoperative serum creatinine levels was the lowest oxygen delivery, with a critical value at 272 mL.min(-1).m(-2). The lowest hematocrit was an independent risk factor with a lowest predictive value at a cutoff of 26%. When corrected for the need for transfusions, only the lowest oxygen delivery remained an independent risk factor. CONCLUSIONS: A high degree of hemodilution during cardiopulmonary bypass is a risk factor for postoperative renal dysfunction; however, its detrimental effects may be reduced by increasing the oxygen delivery with an adequately increased pump flow.

Postoperative antithrombin levels and outcome in cardiac operations.

OBJECTIVE: During cardiac operations with cardiopulmonary bypass surgery, antithrombin is consumed and low levels of antithrombin activity are commonly observed at admission to the intensive care unit (ICU). This study investigates the association between antithrombin activity at admission to the ICU (ICU-antithrombin activity) and various outcome variables. DESIGN: The authors conducted a prospective, observational cohort study. SETTING: The study was conducted at a university hospital. PATIENTS: The study consisted of 647 consecutive patients who had undergone cardiac surgery with cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: ICU-antithrombin activity significantly (p < .001) decreased with respect to preoperative values. As seen with univariate analysis, low levels of ICU-antithrombin activity were significantly associated with higher blood loss, prolonged mechanical ventilation time and ICU stay, a higher incidence of allogeneic blood products use, surgical reexploration, low cardiac output syndrome, adverse neurologic events, thromboembolic events, renal dysfunction, and hospital mortality. When corrected for the other explanatory variables, low levels of ICU-antithrombin activity remained independently associated with a prolonged ICU stay (p = .003) and with a higher incidence of surgical reexploration (p = .023), adverse neurologic events (p = .001), and thromboembolic events (p = .036). An ICU-antithrombin activity value of <58% was found to be predictive of prolonged ICU stay, with a sensitivity of 67% and a specificity of 83%. CONCLUSIONS: Low levels of ICU-antithrombin activity are associated with a poor outcome in cardiac surgery; ICU-antithrombin activity is predictive of prolonged ICU stay.

Determinants of antithrombin consumption in cardiac operations requiring cardiopulmonary bypass.

Antithrombin (AT) is a natural anticoagulant that is consumed during cardiac operations with cardiopulmonary bypass (CPB). This study is an observational trial aimed at identifying the factors determining the magnitude of the AT consumption during cardiac operations. Two hundred and fifty consecutive adult patients undergoing cardiac operations with CPB were admitted to the study. Preoperative and intraoperative variables were tested with respect to their role in determining AT activity at the end of the operation. At a univariate analysis, eight predictors of AT activity at the end of the operation have been identified: preoperative AT activity; age; diabetes on medication; preoperative haematocrit value; preoperative dialysis; combined operation; CPB duration; lowest temperature on CPB. A multivariate predictive model was created, and five factors remained as independent predictors of AT activity at the end of the operation: preoperative AT activity (p = 0.001); age (p = 0.015); combined operation (p = 0.014); diabetes (p = 0.013) and CPB duration (p = 0.001). On this basis, predictive tables of AT consumption have been established for different combinations of risk factors.

Different patterns of heparin resistance: therapeutic implications.

Heparin resistance (HR) during cardiac operations is a common feature. Its aetiology often recognizes a decrease in circulating antithrombin III (AT III) due to a preoperative heparin treatment. Nevertheless, some papers highlighted the existence of HR in patients with normal values of AT III. This paper was designed in order to identify this subgroup of AT III-independent heparin-resistant patients. Five hundred consecutive patients scheduled for coronary revascularization with cardiopulmonary bypass were enrolled in this prospective trial. HR was identified in 104 (20.8%) patients. Thirty-six of them (7.2% of the total population) had a preoperative AT III activity > or = 100%, and were defined as AT III-independent heparin-resistant patients. This subgroup significantly differs from the AT III-dependent heparin-resistant group being affected by a less severe degree of HR and including less patients pretreated with heparin. Unlike the other heparin-resistant patients, these subjects do not respond to AT III supplementation aimed at reaching supranormal AT III activity values.